Modern stage lighting systems are typically controlled by computer-based controlling systems.
The complexity of such stage lighting systems has necessitated increased computing power. There has been a tendency to distribute that increased computing power among the luminaires by making each of the luminaires into an intelligent subsystem.
The distributed computing power is effected by a central processing computer and a number of slave processing computers which accept their commands from the central processing computer.
One example of such a system is the ICON(TM) system made by Light & Sound Design, Ltd., the assignee of the present application. The Light and Sound system uses a central controller ("the ICON controller") to control a plurality of distributed processing units that are located in the ICON lamp units. Each ICON lamp unit has a number of processors controlling various functions of the unit.
An exemplary command from the ICON controller to the ICON unit might be parsed as: go to position X at speed S and be there at time Y. The ICON unit receives this command, and uses its own processor to determine how to drive the motors and when to start, etc, to carry out this command.
According to the preferred embodiment, all of the operations are synchronized to a single clock: a system clock. This has the advantage of requiring maintenance of only one clock.
The inventors recognized that various things, including timing, may change during a performance. Sometimes the tempo of the song they are playing may change between rehearsal and the playing time. Some aspects of the lighting performance may need to be synchronized with that operation.
The inventors of the present invention, having recognized these problems, have devised a feature allowing the timing of operations to be changed globally. A preferred embodiment describes a system where operations of both the main system and the subsystem are tied to the system clock. The system clock can be selectively changed in a way that causes those synchronized operations to operate at a different effective rate. When the time for one clock pulse changes, everything referenced to that clock pulse will change as well. This enables, for example, the tempo provided by the clock to be changed to match the tempo of a particular song being played.
As an example of the way the system could be used, assume a light chase including a plurality of lighting effects. Lighting effect no. 2 follows lighting effect no. 1 and lighting effect no. 3 follows lighting effect no. 2 and so on. This all continues until the end of the chase. The chases can be synchronized with, for example, clock timings.
A system clock is changed in order to change various aspects which are synchronized with that system clock. According to one aspect, a show with sequential lighting events has operations which are timed to coincide with incidents in music. The cues are triggered from a system timing element in the console, and times are controlled by the clock in the console. According to this aspect, the console's effective clock running frequency is modified. The cues remain synchronized with the clock, but since the clock has been changed, the cues occur at different absolute times. This operation is referred to herein as Time Bending (TM).
Specific ways of carrying out this operation are described.